发表机构
The University of Tokyo; Tokyo Metropolitan University; Hokkaido University; RIKEN Center for Emergent Matter Science（东京大学; 东京都立大学; 北海道大学; 理化学研究所新兴物质科学中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出扩展金兹堡-朗道方法，仅对协变梯度项微扰展开，通过微观自由能有限差分计算多带超导体的相干长度和磁穿透深度，与BdG结果吻合且计算量小。
AI 中文摘要
我们提出了一种扩展的金兹堡-朗道（GL）方法，用于计算远低于转变温度 $T_{\mathrm c}$ 的温度下超导相干长度和磁穿透深度。与传统的GL理论（在序参量及其梯度两方面都展开自由能）不同，我们的方法仅对协变梯度项进行微扰展开，同时保留对超导序参量的完整依赖。这些项的系数由在小施加对动量下评估的微观自由能的有限差分确定。该方法适用于单带和多带超导体，因此为纳入更真实的电子结构提供了一个框架。对于本文研究的模型，扩展GL方法在宽温度范围内与实空间Bogoliubov-de Gennes（BdG）计算结果吻合良好，同时所需计算量大幅减少。
英文摘要
We present an extended Ginzburg-Landau (GL) method for calculating the superconducting coherence length and magnetic penetration depth at temperatures well below the transition temperature $T_{\mathrm c}$. In contrast to conventional GL theory, which expands the free energy in both the order parameters and their gradients, our method applies a perturbative expansion only to the covariant-gradient terms, while retaining the full dependence on the superconducting order parameters. The coefficients of these terms are determined from finite differences of microscopic free energies evaluated at small imposed pair momenta. The method applies to both single-band and multiband superconductors and therefore provides a framework for incorporating more realistic electronic structures. For the models examined here, the extended GL method agrees well with real-space Bogoliubov-de Gennes (BdG) calculations over a wide temperature range, while requiring substantially less computational effort.
Comments13 pages, 10 figures, 2 tables
